Materials comprising of two or more polymeric components have achieved considerable technological significance in the last decade or so due to the unique properties often not attainable in their homopolymeric counterparts. In the present work, two such systemsone involving modified thermosets and the other involving thermoplastic polymer blends, have been studied with regard to their morphological and thermal properties. Both systems take the advantage of not only the physical interactions between the components involved but also their themooxidative properties, giving rise to novel properties that have both fundamental and practical importance. The network system consists of a phenolic novolac based epoxy cured in the presence of low molecular weight poly (propylene oxide). The resulting morphology of these polymers has been studied with the help of scanning electron microscopy. / Ph. D.